Traditional sliding gate type valves can be divided into (a) a valve housing which also contains the driving means beside the bed plate, and (b) the movable slide part with valve plate and discharge nozzle. The valve housing is firmly secured onto the bottom of the ladle. The movable slide part is pressed by way of a stationary lid and by means of clamping bolts against the bed plate with a force such that on the one hand the movable slide part does not jam and on the other so that emergence of the liquid metal between the contact surfaces of the bed plate and of the slide plate under the influence of the ferrostatic pressure will be prevented, especially in the case of a full ladle.
Recently, sliding gate valves have become known, which constitute a unit, containing all the parts necessary for the fulfillment of its function as a valve for controlling the flow of molten metal out of the ladle. Such unitary sliding gate valves are designed to be releasably connected with the casting ladle, for example by means of bolts and wedges, that is to say in a simple manner. The advantage of these valve units lies in the fact, that an overhauling, that is to say the removal and replacement of worn-out refractory parts and the re-assembly need not be accomplished in the steel plant, but may be carried out in a central preparatory area. When the unit is removed from the ladle, the nozzle brick insert will remain in the ladle.
The present invention bases on the realization that the temperature conditions of the sliding gate valve unit and its parts that are to be assembled, during tightening of the clamping bolts between the lid and the housing, are of essential importance for the proper operation of the slide.
Therefore it is the aim of the invention to provide an improved process for the assembly of casting ladle slide valve units.